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nanning

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Re: Permafrost general science thread
« Reply #100 on: June 13, 2020, 05:24:06 PM »
Good post jens imo.

In a global all-lifeforms context:
N₂O is a powerful GHG, then there's also the high-impact threat of large marine methane bursts and in general the likely increasing permafrost emissions in all areas that will be warmed up in an accelerating, step-wise manner because of AGW (BAU).

These permafrost emissions are out of our control!
These emissions will go on. Even when we stop with our anthropogenic emissions. And they are accelerating.

Long term (?) consequences:
A hothouse Earth is coming for certain I think, taking the above in consideration together with all other tipping points. A hyperthermal is likely imo. But that is off-topic here. Sorry, just connecting dots. There are many more dots but I realised that I drifted from the thread topic. Cheers.
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kassy

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Re: Permafrost general science thread
« Reply #101 on: June 17, 2020, 06:45:43 AM »
Article about the research in #96:

https://e360.yale.edu/digest/climate-models-underestimate-co2-emissions-from-permafrost-by-14-percent-study-finds

Scientists estimate there are about 1,500 billion metric tons of carbon locked away in Arctic permafrost, and that 5 to 15 percent of this carbon could be emitted as carbon dioxide by 2100 — enough to increase global temperatures 0.3 to 0.4 degrees Celsius. But these estimates do not include the CO2 that forms when permafrost carbon escapes into Arctic lakes and rivers and is oxidized by ultraviolet and visible light, a process known as photomineralization.

Researchers at the University of Michigan studied organic carbon from six different Arctic locations and found that substantial carbon dioxide emissions could be released through photomineralization — enough to raise permafrost-related CO2 emissions by 14 percent.
...
“Only recently have global climate models included greenhouse gases from thawing permafrost soils. But none of them contain this feedback pathway,”

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vox_mundi

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Re: Permafrost general science thread
« Reply #102 on: July 01, 2020, 03:09:45 AM »
Beavers Gnawing Away at the Arctic Permafrost
https://phys.org/news/2020-06-beavers-gnawing-arctic-permafrost.html

Alaska's beavers are profiting from climate change, and spreading rapidly. In just a few years' time, they have not only expanded into many tundra regions where they'd never been seen before; they're also building more and more dams in their new homes, creating a host of new water bodies. This could accelerate the thawing of the permafrost soils, and therefore intensify climate change, as an International American-German research team reports in the journal Environmental Research Letters.


The upper two images are photos taken within the study area in 2016 showing the tundra region setting. The bottom two images are taken from similar tundra across Hotham Inlet in 2015 (lower left) and 2011 (lower right) showing beaver dams in a drained lake basin outlet and along a beaded stream course, respectively.

... Back in 2018, Ingmar Nitze and Guido Grosse from the AWI, together with colleagues from the U.S., determined that the beavers living in an 18,000-square-kilometer section of northwest Alaska had created 56 new lakes in just five years. For their new study, the team from the AWI, the University of Alaska in Fairbanks, and the University of Minnesota in Minneapolis have now taken a closer look at this trend. Using detailed satellite data and extended time series, the experts tracked the beavers' activities in two other regions in Alaska—and were surprised by what they found.

"Of course, we knew that the beavers there had spread substantially over the last few decades," says Nitze. This is partly due to climate change; thanks to rising temperatures, now more and more habitats offer the shrubs that the animals need for food and building material. Furthermore, the lakes, which used to freeze solid, now offer beaver-friendlier conditions, thanks to their thinner seasonal winter ice cover. Lastly, the rodents aren't hunted as intensively as in the past. As a result, it's a good time to be a beaver in the Arctic.

"But we never would have dreamed they would seize the opportunity so intensively," says Nitze. The high-resolution satellite images of the roughly 100-square-kilometer study area near the town of Kotzebue reveal the scale of the animals' activities there. From just two dams in 2002, the number had risen to 98 by 2019—a 5,000-percent increase, with more than 5 new dams being constructed per year. And the larger area surveyed, which covers the entire northern Baldwin Peninsula, also experienced a beaver dam boom. According to Nitze, "We're seeing exponential growth there. The number of these structures doubles roughly every four years."

This has already affected the water balance. Apparently, the rodents intentionally do their work in those parts of the landscape that they can most easily flood. To do so, sometimes they dam up small streams, and sometimes the outlets of existing lakes, which expand as a result. "But they especially prefer drained lake basins," Benjamin Jones, lead author of the study, and Nitze report. In many cases, the bottoms of these former lakes are prime locations for beaver activity. "The animals have intuitively found that damming the outlet drainage channels at the sites of former lakes is an efficient way to create habitat. So a new lake is formed which degrades ice-rich permafrost in the basin, adding to the effect of increasing the depth of the engineered waterbody," added Jones. These actions have their consequences: in the course of the 17-year timeframe studied, the overall water area in the Kotzebue region grew by 8.3 percent. And roughly two-thirds of that growth was due to the beavers.

The researchers suspect that there have been similar construction booms in other regions of the Arctic; accordingly, they now want to expand their 'beaver manhunt' across the Arctic. "The growth in Canada, for example, is most likely even more extreme," says Nitze. And each additional lake thaws the permafrost below it and on its banks. Granted, the frozen soil could theoretically bounce back after a few years, when the beaver dams break; but whether or not the conditions will be sufficiently cold for that to happen is anyone's guess.


Mapping beaver dams in high-resolution satellite imagery available for the northern Baldwin Peninsula, Alaska. The location of individual dams indicated with red arrow and the flow direction with a light blue arrow. (a) A series of four dams at the outlet of a lake, (b) a ~60 m long dam built in a drained lake basin, (c) a series of dams at the outlet of a lake near a confluence with a beaded stream, (d) a series of dams in a channel running through the middle of a drained lake basin, (e) five dams progressing down the outlet channel of a thermokarst lake, and (f) a series of dams in a beaded stream gulch. Examples shown here taken from 2019 images; note differences in scale across image frames. All dams were constructed after 2002.

Benjamin M. Jones et al, Increase in beaver dams controls surface water and thermokarst dynamics in an Arctic tundra region, Baldwin Peninsula, northwestern Alaska, Environmental Research Letters (2020).
https://iopscience.iop.org/article/10.1088/1748-9326/ab80f1
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vox_mundi

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Re: Permafrost general science thread
« Reply #103 on: July 20, 2020, 10:20:19 PM »
40 More Gt of CO2 Baked In: Plant Roots Increase Carbon Emission from Permafrost Soils
https://phys.org/news/2020-07-roots-carbon-emission-permafrost-soils.html

Plant roots in soil stimulate microbial decomposition, a mechanism called the priming effect. An international research team co-lead by Frida Keuper from INRAE and Umeå University and Birgit Wild from Stockholm University shows that the priming effect alone can cause emission of 40 billion tons carbon from permafrost by 2100. The study was published today in Nature Geoscience.

Scientists have previously anticipated that rapidly rising temperatures will drive the emission of 50-100 billion ton permafrost carbon by 2100. On top of that, plant roots feed sugar to the microorganisms in the soil, which the microbes can use to break down more soil organic matter—the priming effect—resulting in even higher greenhouse gas emissions.

The researchers combined maps of plant activity and data on soil carbon content from the Northern Circumpolar Soil Carbon Database with an extensive literature survey on priming and plant root properties, to estimate the priming effect in permafrost ecosystems and its influence on greenhouse gas emissions.

They show that the priming effect increases soil microbial respiration by 12 percent, which causes the additional loss of 40 billion tons of carbon by 2100 compared to current predictions for permafrost. This equals almost a quarter of the remaining "carbon budget" for human activities to limit global warming to max 1.5°C.

Carbon loss from northern circumpolar permafrost soils amplified by rhizosphere priming, Nature Geoscience (2020).
https://www.nature.com/articles/s41561-020-0607-0
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vox_mundi

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Re: Permafrost general science thread
« Reply #104 on: July 25, 2020, 02:53:37 AM »
Alaska Is Getting Wetter. That's Bad News for Permafrost and the Climate
https://phys.org/news/2020-07-alaska-wetter-bad-news-permafrost.html

Alaska is getting wetter. A new study spells out what that means for the permafrost that underlies about 85% of the state, and the consequences for Earth's global climate.

The study, published today in Nature Publishing Group journal Climate and Atmospheric Science, is the first to compare how rainfall is affecting permafrost thaw across time, space, and a variety of ecosystems. It shows that increased summer rainfall is degrading permafrost across the state.

As Siberia remains in the headlines for record-setting heat waves and wildfires, Alaska is experiencing the rainiest five years in its century-long meteorological record. Extreme weather on both ends of the spectrum—hot and dry versus cool and wet—are driven by an aspect of climate change called Arctic amplification.
"In our research area the winter has lost almost three weeks to summer," says study lead author and Fairbanks resident Thomas A. Douglas, who is a scientist with the U.S. Army Cold Regions Research and Engineering Laboratory. "This, along with more rainstorms, means far more wet precipitation is falling every summer."

Over the course of five years, the research team took 2750 measurements of how far below the land's surface permafrost had thawed by the end of summer across a wide range of environments near Fairbanks, Alaska. The five-year period included two summers with average precipitation, one that was a little drier than usual, and the top and third wettest summers on record. Differences in annual rainfall were clearly imprinted in the amount of permafrost thaw.

More rainfall led to deeper thaw across all sites. After the wettest summer in 2014, permafrost didn't freeze back to previous levels even after subsequent summers were drier. Wetlands and disturbed sites, like trail crossings and clearings, showed the most thaw. Tussock tundra, with its deep soils and covering of tufted grasses, has been found to provide the most ecosystem protection of permafrost. While permafrost was frozen closest to the surface in tussock tundra, it experienced the greatest relative increase in the depth of thaw in response to rainfall, possibly because water could pool on the flat surface. Forests, especially spruce forests with thick sphagnum moss layers, were the most resistant to permafrost thaw. Charlie Koven, an Earth system modeler with the Lawrence Berkeley National Laboratory, used the field measurements to build a heat balance model that allowed the team to better understand how rain was driving heat down into the permafrost ground.


Relationships between active layer depth and summer precipitation.

Thomas A. Douglas et al, Increased rainfall stimulates permafrost thaw across a variety of Interior Alaskan boreal ecosystems, npj Climate and Atmospheric Science (2020)
https://www.nature.com/articles/s41612-020-0130-4
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kassy

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Re: Permafrost general science thread
« Reply #105 on: July 25, 2020, 07:46:42 AM »
Experiments Reveal How Permafrost Carbon Becomes Carbon Dioxide

Field samples from Alaska show how sunlight and iron convert permafrost carbon to carbon dioxide. Climate models ignore this process.

...

Researchers have now experimentally studied how sunlight triggers carbon dioxide production from permafrost carbon that’s been flushed to lakes and rivers, a process long ignored in climate models.

Current estimates of global warming from permafrost carbon feedback are biased low, the team concluded.

...

Microbes and Sunlight
One way in which permafrost carbon gets converted to carbon dioxide is via microbes—some microscopic life-forms chow down on carbon and respire carbon dioxide.

Although this microbial process is generally taken into account in climate models, comparably little is known about the permafrost carbon that’s flushed to lakes and rivers, where it’s exposed to sunlight. “We’ve known for a while that sunlight converts organic carbon to carbon dioxide, but the governing control of this process has escaped us,” said Ward.

It’s been hypothesized that this photomineralization might be controlled by the presence of iron, which is abundant in Arctic fresh waters. “There have been lots of lab-based studies suggesting that iron is a key player, but this is the first to let nature tell us what controls this process,” said Ward.

In 2018, Ward and his colleagues collected five samples of permafrost from northern Alaska. Back in the laboratory, they thawed the permafrost, filtered out the microbes, and isolated the dissolved organic carbon and other constituents, including iron. They then exposed the samples to different wavelengths of ultraviolet and visible light.

Visible Light Wins
In nature, the highest rates of photomineralization occur in the presence of visible light, Ward and his colleagues calculated. Two factors contribute to this finding. First, Earth’s surface receives significantly more visible light than ultraviolet light. Second, iron kick-starts reactions at longer wavelengths, the team showed. (Visible light is characterized by longer wavelengths than ultraviolet light.)

Photomineralization’s wavelength dependence has important implications, said Ward. It means that permafrost carbon in deep lakes or rivers is still apt to be converted to carbon dioxide. “As you move deeper into the water column, there’s less ultraviolet light available and more visible light,” said Ward.

Older and More Effective
The researchers also determined that the older carbon found in permafrost—several thousand years old—was roughly twice as effective at producing carbon dioxide as modern carbon. Modern carbon has more sunlight-absorbing compounds, said team member Jenny Bowen, a biogeochemist at the University of Michigan, but permafrost carbon is better at reaping the reaction-promoting benefits of iron.

This unaccounted-for contribution from old carbon has the potential to fundamentally change the carbon cycle, said Ted Schuur, an ecosystem ecologist at Northern Arizona University in Flagstaff not involved in the research. “Stuff that wasn’t part of the atmosphere is suddenly ending up in the atmosphere.”
Since photomineralization of permafrost carbon isn’t presently included in climate models, estimates of future global warming are biased low, the researchers concluded. “Sunlight increases the amount of carbon dioxide coming from thawing permafrost by 14%,” said Bowen. “The planet will warm even more than expected.”

These results were published last month in Geophysical Research Letters.

...

https://eos.org/articles/experiments-reveal-how-permafrost-carbon-becomes-carbon-dioxide



Arctic Amplification of Global Warming Strengthened by Sunlight Oxidation of Permafrost Carbon to CO2

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020GL087085

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Re: Permafrost general science thread
« Reply #106 on: August 11, 2020, 03:02:10 PM »
Anthrax Outbreak In Russia Thought To Be Result Of Thawing Permafrost

Quote
Russia is fighting a mysterious anthrax outbreak in a remote corner of Siberia. Dozens of people have been hospitalized; one child has died. The government airlifted some families out because more than 2,000 reindeer have been infected.

Link >> https://www.npr.org/sections/goatsandsoda/2016/08/03/488400947/anthrax-outbreak-in-russia-thought-to-be-result-of-thawing-permafrost

kassy

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Re: Permafrost general science thread
« Reply #107 on: August 12, 2020, 12:26:45 PM »
Climate change: Warming world will be 'devastating' for frozen peatlands

The world's peatlands will become a large source of greenhouse gases as temperatures rise this century, say scientists.

Right now, huge amounts of carbon are stored in boggy, often frozen regions stretching across northern parts of the world.

But much of the permanently frozen land will thaw this century, say experts.

This will release warming gases at a rate that could be 30-50% greater than previous estimates.

Using data compiled from more than 7,000 field observations, the authors of this new study were able to generate the most accurate maps to date of the peatlands, their depth and the amount of warming gases they contain.

They show that the boggy terrain covers 3.7 million sq kilometres (1.42 million sq miles).

...

"But my best estimate is that this shift will occur in the second half of this century."

....

If this new peatland estimate is included with all the estimates for permafrost melting, it is projected to equal the annual emissions of the EU and UK by 2100.

"The only way to limit the permafrost carbon feedback is to reduce global warming," said Dr Hugelius.

https://www.bbc.com/news/science-environment-53726487

So this is both permafrost and non permafrost peatlands combined. That of course does not matter for the planet.

Large stocks of peatland carbon and nitrogen are
vulnerable to permafrost thaw
https://www.pnas.org/content/pnas/early/2020/08/04/1916387117.full.pdf
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morganism

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Re: Permafrost general science thread
« Reply #108 on: August 22, 2020, 07:13:48 PM »
Electric mud’ teems with new, mysterious bacteria

"The bacteria also alter the mud’s chemistry, making layers closer to the surface more alkaline and deeper layers more acidic, Malkin has found. Such pH gradients can affect “numerous geochemical cycles,” she says, including those involving arsenic, manganese, and iron, creating opportunities for other microbes.

With vast swaths of the planet covered by mud, cable and nanowire bacteria are likely having an influence on global climate, researchers say. Nanowire bacteria, for example, can strip electrons from organic materials, such as dead diatoms, then shuttle them to other bacteria that produce methane—a potent greenhouse gas. Under different circumstances, cable bacteria can reduce methane production.

https://www.sciencemag.org/news/2020/08/electric-mud-teems-new-mysterious-bacteria


BornFromTheVoid

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Re: Permafrost general science thread
« Reply #109 on: August 27, 2020, 11:45:35 AM »
New paper is available now, feel free to ask any question about it.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL087917

Abstract
High overall rates of permafrost cliff retreat, coupled with spatial variability, have been accompanied by increased uncertainty over future landscape dynamics. We map long‐term (>80 years) retreat of the shoreline and photogrammetrically analyze historic aerial imagery to quantify the processes at a permafrost coast site with massive ground ice. Retreat rates have been relatively constant but topographic changes show that subsidence is a potentially critical but often ignored component of coastal sensitivity, exceeding landward recession by over 3 times during the last 24 years. We calibrate novel passive seismic surveys along clear and variable exposures of massive ground ice and then spatially map key sub‐surface layers. Combining decadal patterns of volumetric change with new ground ice variation maps enables past trends to be interpreted, future volumetric geomorphic behavior to be better constrained, and improves the assessment of permafrost coast sensitivity and the release of carbon‐bearing material.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Tor Bejnar

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Re: Permafrost general science thread
« Reply #110 on: August 27, 2020, 05:39:26 PM »
I wasn't familiar with the term "ground ice", so I looked it up on the inter-tubey thing:
From Glossary of Permafrost and Related Ground-Ice Terms (a PDF)
Quote
ice, ground (see also ice, buried; ice, epigenetic; ice, intrusive; ice,
syngenetic)
[glace de sol]
A general term referring to all types of ice formed in freezing and frozen
ground(see Figure 10).
COMMENT: Ground ice occurs in pores, cavities, voids or other
openings in soil or rock and includes massiveice, but generally excludes
buriedice. Ground ice may be epigenetic or syngenetic,
contemporaneous or relict, aggrading or degrading, perennial or
seasonal. It may occur as lenses, wedges, veins, sheets, seams, irregular
masses, or as individual crystals or coatings on mineral or organic
particles. Perennial ground ice can only occur within permafrost bodies.
REFERENCES: Mackay, 1972b; Pollard and French, 1980.

So (from reading the plain language offering), when climate warms, permafrost melts.  A couple things happen:
  • what was once hard (frozen hard) is now soft and erodible
  • what was once frozen H2O in the ground is now liquid and it flows away, causing the surface to 'slump' (locally or widespread)
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longwalks1

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Re: Permafrost general science thread
« Reply #111 on: August 27, 2020, 06:38:08 PM »
A short quote from BFV #109 post for  https://doi.org/10.1029/2020GL087917        Massive Ice Control on Permafrost Coast Erosion and Sensitivity

Quote
2.Regional Setting and Methods The Tuktoyaktuk Coastlands, northwest Canada,arelocated within the southern Beaufort Sea area  and aredominated  by  ice-rich permafrost landscapes(Rampton,  1988).  Thisgenerally flat, deltaiclandscape is punctuated by ice cored plateaus and domes acrossthe tundra. Here, we focus on Peninsula Point(Figure 1a), 6 km southwest of Tuktoyaktukandwithin the Pingo Canadian Landmark (a national historic site managed by Parks Canada), itis a representative type-site  for  intrasedimental  massive  ice (Gilbert  et  al.,  2016;  Mackay  &  Dallimore,  1992; Murton,  2009). Compoundingthe dynamic  erosion  processesin  the  area (Murton,  2005), reduced sea-ice (Overeem et al., 2011)and frozen ground seasons (Laberge & Payette, 1995; Liljedahl et al., 2016), increasing storm intensity (Vermaire et al., 2013)and a relative 2.5 mm a-1sea-level rise (Hill et al., 1993)have intensified the degradation of permafrost coasts in the region

Passive seismic surveys, nicer to the larger fauna, the caribou need all the TLC that they can get.   

Quote
3.2Mapping subsurface structure of massive iceThis work demonstrates that passive seismic surveys can determine the presence and depth of massive ice within challenging permafrost coast ground conditions.

Just a stellar usage of old data and new right sized technology. 

Just west of Tuktoyatuk.  About 30 - 35 km east of the McKenzie.  Quick background of the scene at
https://en.wikipedia.org/wiki/Pingo_National_Landmark

BornFromTheVoid

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Re: Permafrost general science thread
« Reply #112 on: August 27, 2020, 08:40:14 PM »
I wasn't familiar with the term "ground ice", so I looked it up on the inter-tubey thing:
From Glossary of Permafrost and Related Ground-Ice Terms (a PDF)
Quote
ice, ground (see also ice, buried; ice, epigenetic; ice, intrusive; ice,
syngenetic)
[glace de sol]
A general term referring to all types of ice formed in freezing and frozen
ground(see Figure 10).
COMMENT: Ground ice occurs in pores, cavities, voids or other
openings in soil or rock and includes massiveice, but generally excludes
buriedice. Ground ice may be epigenetic or syngenetic,
contemporaneous or relict, aggrading or degrading, perennial or
seasonal. It may occur as lenses, wedges, veins, sheets, seams, irregular
masses, or as individual crystals or coatings on mineral or organic
particles. Perennial ground ice can only occur within permafrost bodies.
REFERENCES: Mackay, 1972b; Pollard and French, 1980.

So (from reading the plain language offering), when climate warms, permafrost melts.  A couple things happen:
  • what was once hard (frozen hard) is now soft and erodible
  • what was once frozen H2O in the ground is now liquid and it flows away, causing the surface to 'slump' (locally or widespread)

We were dealing with a site that was specifically know for its massive ice bodies. These are thick  layers, up to 10s of meters, covered by permafrost and usually with permafrost below them too.

Here's an example from the field site, with the SfM models we used too.


We examined the erosion process called retrogressive thaw slumps. Where cliffs form over these massive ice bodies and spread inland really quickly. They can cause so much material to flow towards the shoreline that it results in large mud lobes causing transient progradation, like the lobe in the pic above. This means you get mass loss through vertical changes in the landscape several times faster than from shoreline retreat
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

BornFromTheVoid

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Re: Permafrost general science thread
« Reply #113 on: August 27, 2020, 08:44:21 PM »
A short quote from BFV #109 post for  https://doi.org/10.1029/2020GL087917        Massive Ice Control on Permafrost Coast Erosion and Sensitivity

Quote
2.Regional Setting and Methods The Tuktoyaktuk Coastlands, northwest Canada,arelocated within the southern Beaufort Sea area  and aredominated  by  ice-rich permafrost landscapes(Rampton,  1988).  Thisgenerally flat, deltaiclandscape is punctuated by ice cored plateaus and domes acrossthe tundra. Here, we focus on Peninsula Point(Figure 1a), 6 km southwest of Tuktoyaktukandwithin the Pingo Canadian Landmark (a national historic site managed by Parks Canada), itis a representative type-site  for  intrasedimental  massive  ice (Gilbert  et  al.,  2016;  Mackay  &  Dallimore,  1992; Murton,  2009). Compoundingthe dynamic  erosion  processesin  the  area (Murton,  2005), reduced sea-ice (Overeem et al., 2011)and frozen ground seasons (Laberge & Payette, 1995; Liljedahl et al., 2016), increasing storm intensity (Vermaire et al., 2013)and a relative 2.5 mm a-1sea-level rise (Hill et al., 1993)have intensified the degradation of permafrost coasts in the region

Passive seismic surveys, nicer to the larger fauna, the caribou need all the TLC that they can get.   

Quote
3.2Mapping subsurface structure of massive iceThis work demonstrates that passive seismic surveys can determine the presence and depth of massive ice within challenging permafrost coast ground conditions.

Just a stellar usage of old data and new right sized technology. 

Just west of Tuktoyatuk.  About 30 - 35 km east of the McKenzie.  Quick background of the scene at
https://en.wikipedia.org/wiki/Pingo_National_Landmark

Cheers!
The combination of the passive seismics with the cm scale surface models generated from drone imagery meant we could create 3D models of sections of the site too. That way we can figure out how much of the ground is soil vs ice. This matters for how fast it will erode, the mechanism by which it will erode, and knowing the constituents (ice vs soil) we can better constrain the volume of carbon that will be released too.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Tor Bejnar

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Re: Permafrost general science thread
« Reply #114 on: August 27, 2020, 08:46:49 PM »
cleaned up quotes (without actual access to paper):
Quote
    2. Regional Setting and Methods.  The Tuktoyaktuk Coastlands, northwest Canada, are located within the southern Beaufort Sea area and are dominated by ice-rich permafrost landscapes (Rampton, 1988).  This generally flat, deltaic landscape is punctuated by ice cored plateaus and domes across the tundra.  Here, we focus on Peninsula Point (Figure 1a), 6 km southwest of Tuktoyaktuk and within the Pingo Canadian Landmark (a national historic site managed by Parks Canada), it is a representative type-site  for  intrasedimental massive ice (Gilbert et al., 2016; Mackay & Dallimore, 1992; Murton, 2009). Compounding the dynamic erosion processes in  the area (Murton, 2005), reduced sea-ice (Overeem et al., 2011) and frozen ground seasons (Laberge & Payette, 1995; Liljedahl et al., 2016), increasing storm intensity (Vermaire et al., 2013) and a relative 2.5 mm a-1 sea-level rise (Hill et al., 1993) have intensified the degradation of permafrost coasts in the region.




    3.2 Mapping subsurface structure of massive ice.  This work demonstrates that passive seismic surveys can determine the presence and depth of massive ice within challenging permafrost coast ground conditions.
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Tor Bejnar

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Re: Permafrost general science thread
« Reply #115 on: August 27, 2020, 09:24:13 PM »
I've read a tiny bit about "retrogressive thaw slumps"  and was aware of how fast a multi-meter thick area (volume) of recent permafrost can mobilize, flowing into streams or the sea ("mud flows," we used to call them). 

I wasn't aware of how thick 'pure' ice could be within the permafrost.  At first (just now) I wondered how 'lenses' grew so thick, but then imagined a (10s-to-100s-of-centuries long) series of freeze/thaw [just above the ice] cycles could built up the ice layer to basically any thickness.  (I don't presume to understand the actual physics ... and my imagination is just my imagination.) 

Wow!  'Wouldn't want to be walking around that area on the wrong day!

A neighbor in New Hampshire, one Summer, paved his long-used mostly dirt driveway, and the next Spring (Mud Season) his pickup truck (well, one wheel) fell through the pavement up to its axle.  Solid ground really can become "quicksand". 
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BornFromTheVoid

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Re: Permafrost general science thread
« Reply #116 on: August 27, 2020, 10:27:58 PM »
I've read a tiny bit about "retrogressive thaw slumps"  and was aware of how fast a multi-meter thick area (volume) of recent permafrost can mobilize, flowing into streams or the sea ("mud flows," we used to call them). 

I wasn't aware of how thick 'pure' ice could be within the permafrost.  At first (just now) I wondered how 'lenses' grew so thick, but then imagined a (10s-to-100s-of-centuries long) series of freeze/thaw [just above the ice] cycles could built up the ice layer to basically any thickness.  (I don't presume to understand the actual physics ... and my imagination is just my imagination.) 

Wow!  'Wouldn't want to be walking around that area on the wrong day!

A neighbor in New Hampshire, one Summer, paved his long-used mostly dirt driveway, and the next Spring (Mud Season) his pickup truck (well, one wheel) fell through the pavement up to its axle.  Solid ground really can become "quicksand".

The one on Peninsula Point formed as the Laurentide ice sheet was retreating, so the ground was freezing but there was loads of subsurface meltwater flowing and freezing too. it may have been up to 20 m thick at one stage.

The number and growth of thaw slumps are crazy. This study from the nearby Banks Island, showing a 60 fold increase in their numbers since the mid 80s

https://www.nature.com/articles/s41467-019-09314-7

I have some cool pics and animation of the slumps too. I'll post them up tomorrow if I get the time. You can literally watch them developing just standing there.
I recently joined the twitter thing, where I post more analysis, pics and animations: @Icy_Samuel

Sebastian Jones

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Re: Permafrost general science thread
« Reply #117 on: August 28, 2020, 12:22:59 AM »
I've read a tiny bit about "retrogressive thaw slumps"  and was aware of how fast a multi-meter thick area (volume) of recent permafrost can mobilize, flowing into streams or the sea ("mud flows," we used to call them). 
........................


The one on Peninsula Point formed as the Laurentide ice sheet was retreating, so the ground was freezing but there was loads of subsurface meltwater flowing and freezing too. it may have been up to 20 m thick at one stage.

The number and growth of thaw slumps are crazy. This study from the nearby Banks Island, showing a 60 fold increase in their numbers since the mid 80s

https://www.nature.com/articles/s41467-019-09314-7

I have some cool pics and animation of the slumps too. I'll post them up tomorrow if I get the time. You can literally watch them developing just standing there.

We have a community science thaw slump monitoring project on the Dempster Highway- the road that leads (most of the way) to BFTV's study area.
I'd love to read the entire paper, is there a way to get it out from behind the paywall? SciHub does not have it yet.

gerontocrat

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Re: Permafrost general science thread
« Reply #118 on: October 02, 2020, 09:38:35 PM »
This one is about the cascading effects of permafrost thaw on slopes - in NW Canada, but must be applicable over all the permafrosted tundra.

Quote
Short summary
We address knowledge gaps in the understanding the climate-driven amplification of slope thermokarst, the evolution of downstream linkages, and the cascade of consequences. The non-linear intensification of thaw-driven landslides in glaciated permafrost terrain of northwestern Canada has strengthened slope to stream connectivity. Primary effects to headwater systems indicate the major potential for long-term impacts and their propagation across watershed scales to coastal environments.
https://tc.copernicus.org/preprints/tc-2020-218/tc-2020-218.pdf
Permafrost thaw couples slopes with downstream systems and effects propagate through Arctic drainage networks
Quote
Abstract.
The intensification of thaw-driven mass wasting is transforming glacially-conditioned permafrost terrain, coupling slopes with aquatic systems, and triggering a cascade of downstream effects. Within the context of recent, rapidly evolving climate controls on the geomorphology of permafrost terrain we:
A) quantify three-dimensional slump enlargement and described the processes and thresholds coupling slopes to downstream systems;
B) investigate catchment-scale patterns of slope thermokarst (thaw slumps and slides) impacts and the geomorphic implications; and
C) project the propagation of effects through hydrological networks draining continuous permafrost of northwestern Canada.

Power-law relationships between thaw-slump area and volume (R2 = 0.90), and thickness of permafrost thawed (R2 = 0.63), combined with the multi-decadal (1985–2018) increase in areal extent of thaw-slump disturbance show a two-order of magnitude increase in catchment-scale geomorphic activity and the coupling of slope and hydrological systems.

Predominant catchment effects are to first- and second-order streams where sediment delivery commonly exceeds stream transport capacity by orders of magnitude indicating millennial-scale perturbation of downstream systems. Assessment of hydrological networks indicates thaw-driven mass wasting directly affects over 6,760 km of stream segments, 890 km of coastline, and 1,370 lakes in the 994,860 km2 study area.

Downstream propagation of slope thermokarst indicates a potential increase in the number of affected lakes by at least a factor of 4 (n > 5,600), impacted stream length by a factor of 7 (> 48,000 km) and defines several major impact zones to lakes, deltas, and coastal areas. Prince of Wales Strait is the receiving marine environment for greatly increased sediment and geochemical fluxes from numerous slump impacted hydrological networks draining the landmasses of Banks and Victoria Islands. Peel and Mackenzie Rivers are globally significant conveyors of the slope thermokarst cascade delivering effects to North America’s largest Delta and the Beaufort Sea.

Climate-driven erosion of ice-rich slopes in permafrost preserved glaciated terrain has triggered a time-transient cascade of downstream effects that signal the renewal of post-glacial landscape evolution. Glacial legacy and the patterns of continental drainage dictate that terrestrial, freshwater and marine environments of western Arctic Canada will be an interconnected hotspot of thaw-driven change through the coming millennia.
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Re: Permafrost general science thread
« Reply #119 on: October 03, 2020, 03:01:47 AM »
I just went straight to the article. The phrases "non-linear increase",   "2 order of magnitude increase",   just jumped out at me.  Going back to the summation I see you italicized those.      I await comment from BTFV and others over the article especially  the Tuktoyaktuk  Coastland  implications.  Wow.   

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Re: Permafrost general science thread
« Reply #120 on: October 04, 2020, 01:20:44 AM »
"Permafrost is melting from the top-down and bottom-up."  Response of Vladimir Romanovsky Professor at International Arctic Research Center, Fairbanks Alaska; to a question from Elizabeth Kolbert in her 2006 book "Field Notes from a Catastrophe".  Professor Romanovsky installed a series of temperature gauges in boreholes across a section of Alaskan permafrost.  He's been studying Alaskan permafrost for at least 20 years. Haven't had time to catch up on his publications. He can be reached at veromanovsky@alaska.edu. 

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Re: Permafrost general science thread
« Reply #121 on: October 16, 2020, 09:49:46 PM »
Arctic Ocean Sediments Reveal Permafrost Thawing During Past Climate Warming
https://phys.org/news/2020-10-arctic-ocean-sediments-reveal-permafrost.html

Sea floor sediments of the Arctic Ocean can help scientists understand how permafrost responds to climate warming. A multidisciplinary team from Stockholm University has found evidence of past permafrost thawing during climate warming events at the end of the last ice age. Their findings, published in Science Advances, caution about what could happen in the near future: That Arctic warming by only a few degrees Celsius may trigger massive permafrost thawing, coastal erosion, and the release of the greenhouse gases carbon dioxide (CO2) and methane (CH4) into the atmosphere.

... "Our new study shows for the first time the full history of how warming at the end of the last ice age triggered permafrost thawing in Siberia. This also suggests the release of large quantities of greenhouse gases," says Jannik Martens, Ph.D. student at Stockholm University and lead author of the study. "It appears likely that past permafrost thawing at times of climate warming, about 14,700 and 11,700 years ago, was in part also related to the increase in CO2 concentrations that is seen in Antarctic ice cores for these times. It seems that Arctic warming by only a few degrees Celsius is sufficient to disturb large areas covered by permafrost and potentially affect the climate system."

In the current study, the scientists used an eight meters long sediment core that was recovered from the sea floor more than 1 000 meters below the surface of the Arctic Ocean during the SWERUS-C3 expedition onboard the Swedish icebreaker Oden back in 2014. To reconstruct permafrost thawing on land, the scientists applied radiocarbon (14C) dating and molecular analysis to trace organic remains that once were released by thawing permafrost and then washed into the Arctic Ocean.

"From this core we also learned that erosion of permafrost coastlines was an important driving force for permafrost destruction at the end of the last ice age. Coastal erosion continues to the present day, though ten times slower than during these earlier rapid warming period. With the recent warming trends, however, we see again an acceleration of coastal erosion in some parts of the Arctic, which is expected to release greenhouse gases by degradation of the released organic matter," says Örjan Gustafsson, Professor at Stockholm University and leader of the research program. "Any release from thawing permafrost mean that there is even less room for anthropogenic greenhouse gas release in the earth-climate system budget before dangerous thresholds are reached.

Gustafsson, Martens and their colleagues are now again in the Arctic Ocean as part of the International Siberian Shelf Study (ISSS-2020) onboard the Russian research vessel Akademik Keldysh. The expedition left the port of Arkhangelsk on September 26 and is currently in the East Siberian Sea, seeking more answers to how changing climate may trigger release of carbon, including greenhouse gases, from Arctic permafrost systems, including coastal erosion and permafrost below the sea bottom preserved from the past ice age.



Remobilization of dormant carbon from Siberian-Arctic permafrost during three past warming events. Sci. Adv. 6, eabb6546 (2020)
https://advances.sciencemag.org/content/6/42/eabb6546



... This demonstrates that Arctic warming by only a few degrees may suffice to abruptly activate large-scale permafrost thawing, indicating a sensitive trigger for a threshold-like permafrost climate change feedback.
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gerontocrat

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Re: Permafrost general science thread
« Reply #122 on: October 18, 2020, 01:59:09 PM »
I didn't expect Tsunamis to be a permafrost melting consequence that is becoming a probability rather than a possibility.

https://www.theguardian.com/environment/2020/oct/18/alaska-climate-change-tsunamis-melting-permafrost
Alaska's new climate threat: tsunamis linked to melting permafrost
Quote
In Alaska and other high, cold places around the world, new research shows that mountains are collapsing as the permafrost that holds them together melts, threatening tsunamis if they fall into the sea.

Scientists are warning that populated areas and major tourist attractions are at risk.

One area of concern is a slope of the Barry Arm fjord in Alaska that overlooks a popular cruise ship route.

The Barry Arm slide began creeping early last century, sped up a decade ago, and was discovered this year using satellite photos. If it lets loose, the wave could hit any ships in the area and reach hundreds of meters up nearby mountains, swamping the popular tourist destination and crashing as high as 10 meters over the town of Whittier. Earlier this year, 14 geologists warned that a major slide was “possible” within a year, and “likely” within 20 years.

In 2015, a similar landslide, on a slope that had also crept for decades, created a tsunami that sheared off forests 193 meters up the slopes of Alaska’s Taan Fiord.

“When the climate changes,” said geologist Bretwood Higman, who has worked on Taan Fiord and Barry Arm, “the landscape takes time to adjust. If a glacier retreats really quickly it can catch the surrounding slopes by surprise – they might fail catastrophically instead of gradually adjusting.”

After examining 30 years of satellite photos, for instance, geologist Erin Bessette-Kirton has found that landslides in Alaska’s St Elias mountains and Glacier Bay correspond with the warmest years.

Warming clearly leads to slides, but knowing just when those slides will release is a much harder problem. “We don’t have a good handle on the mechanism,” Bessette-Kirkton said. “We have correlations, but we don’t know the driving force. What conditions the landslide, and what triggers it?”

Adding to the problem, global heating has opened up water for landslides to fall in. A recent paper by Dan Shugar, a geomorphologist at the University of Calgary, shows that as glaciers have shrunk, glacial lakes have grown, ballooning 50% in both number and size in 18 years. In the ocean, fjords lengthen as ice retreats. Slopes that used to hang over ice now hang over water.

Over the past century, 10 of the 14 tallest tsunamis recorded happened in glaciated mountain areas. In 1958, a landslide into Alaska’s Lituya Bay created a 524-meter wave – the tallest ever recorded. In Alaska’s 1964 earthquake, most deaths were from tsunamis set off by underwater landslides.

To deal with the hazard, experts hope to predict when a slope is more likely to fail by installing sensors on the most dangerous slopes to measure the barely perceptible acceleration of creeping that may presage a slide.
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kassy

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Re: Permafrost general science thread
« Reply #123 on: October 26, 2020, 01:24:12 PM »
The linked reference uses new paleo-findings to indicate that the risk of an abrupt remobilization of dormant carbon in the Siberian-Arctic permafrost is higher than previously assumed by consensus climate scientists.  This is particularly true if abrupt sea level rise floods coastal Arctic permafrost regions in coming decades:

Jannik Martens et al (16 Oct 2020), "Remobilization of dormant carbon from Siberian-Arctic permafrost during three past warming events", Science Advances, Vol. 6, no. 42, eabb6546, DOI: 10.1126/sciadv.abb6546

https://advances.sciencemag.org/content/6/42/eabb6546

Abstract
Carbon cycle models suggest that past warming events in the Arctic may have caused large-scale permafrost thaw and carbon remobilization, thus affecting atmospheric CO2 levels. However, observational records are sparse, preventing spatially extensive and time-continuous reconstructions of permafrost carbon release during the late Pleistocene and early Holocene. Using carbon isotopes and biomarkers, we demonstrate that the three most recent warming events recorded in Greenland ice cores—(i) Dansgaard-Oeschger event 3 (~28 ka B.P.), (ii) Bølling-Allerød (14.7 to 12.9 ka B.P.), and (iii) early Holocene (~11.7 ka B.P.)—caused massive remobilization and carbon degradation from permafrost across northeast Siberia. This amplified permafrost carbon release by one order of magnitude, particularly during the last deglaciation when global sea-level rise caused rapid flooding of the land area thereafter constituting the vast East Siberian Arctic Shelf. Demonstration of past warming-induced release of permafrost carbon provides a benchmark for the sensitivity of these large carbon pools to changing climate.

See also:

Title: "New Climate Warnings in Old Permafrost: 'It’s a Little Scary Because it’s Happening Under Our Feet.'"

https://insideclimatenews.org/news/16102020/permafrost-study-arctic-ocean-climate-change

Extract: "The study, published today in Science Advances, shows that only a few degrees of warming in the Arctic is enough "to abruptly activate large-scale permafrost thawing," suggesting a "sensitive trigger" for greenhouse gas emissions from thawing permafrost. The results also support climate models that have shown "large injections of CO2 into the atmosphere" when glaciers, and the frozen lands beneath them, melted.

"If we consider the magnitude and the speed of anthropogenic climate warming, by 1 degree Celsius (1.8 Fahrenheit) globally and 2 degrees Celsius (3.6 Fahrenheit) in the Arctic, during the past 150 years, and compare this with the first abrupt temperature increase of about 1 degree Celsius at the Bölling-Alleröd, it appears likely that large-scale permafrost thawing and carbon release is going to happen again," he said. "Our study indeed suggests that abrupt permafrost thawing represents a tipping point in the climate system.""

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morganism

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Re: Permafrost general science thread
« Reply #124 on: October 27, 2020, 02:29:51 AM »
this is partly OT but,


Microbial Diversity Below The Seafloor Is As Rich As On Earth's Surface



"D'Hondt analyzed 299 samples of marine sediment collected as core samples from 40 sites around the globe. Their sample depths ranged from the seafloor to 678 meters below it. To accurately determine the diversity of microbial communities, the authors extracted and sequenced DNA from each frozen sample under the same clean laboratory condition.

The 16S rRNA gene sequences (approximately 50 million sequences) obtained through comprehensive next-generation sequencing were analyzed to determine microbial community composition in each sample. From these 50 million sequences, the research team discovered nearly 40,000 different types of microorganisms in marine sediment, with diversity generally decreasing with depth. The team found that microbial community composition differs significantly between organic-rich sediment of continental margins and nutrient-poor sediment of the open ocean, and that the presence or absence of oxygen and the concentration of organic matter are major factors in determining community composition.

By comparing their results to previous studies of topsoil and seawater, the researchers discovered that each of these three global biomes--marine sediment, topsoil, and seawater--has different microbial communities but similar total diversity. "It was an unexpected discovery that microbial diversity in the dark, energy-limited world beneath the seafloor is as diverse as in Earth's surface biomes," said Hoshino.

Furthermore, by combining the estimates of bacterial and archaeal diversity for these three biomes, the researchers found that bacteria are far more diverse than archaea--microbes distinct from bacteria and known for living in extreme environments--on Earth."

http://astrobiology.com/2020/10/microbial-diversity-below-the-seafloor-is-as-rich-as-on-earths-surface.html


kassy

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Re: Permafrost general science thread
« Reply #125 on: October 27, 2020, 01:43:34 PM »
Maybe even completely since the articl/paper does not mention permafrost at all.
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gerontocrat

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Re: Permafrost general science thread
« Reply #126 on: October 27, 2020, 04:57:15 PM »
But we have to wait for a peer-reviewd paper next year to find out how whoops! it really is.

https://www.theguardian.com/science/2020/oct/27/sleeping-giant-arctic-methane-deposits-starting-to-release-scientists-find
'Sleeping giant' Arctic methane deposits starting to release, scientists find
Exclusive: expedition discovers new source of greenhouse gas off East Siberian coast has been triggered

Quote
Scientists have found evidence that frozen methane deposits in the Arctic Ocean – known as the “sleeping giants of the carbon cycle” – have started to be released over a large area of the continental slope off the East Siberian coast, the Guardian can reveal.

High levels of the potent greenhouse gas have been detected down to a depth of 350 metres in the Laptev Sea near Russia, prompting concern among researchers that a new climate feedback loop may have been triggered that could accelerate the pace of global heating.

The slope sediments in the Arctic contain a huge quantity of frozen methane and other gases – known as hydrates. Methane has a warming effect 80 times stronger than carbon dioxide over 20 years. The United States Geological Survey has previously listed Arctic hydrate destabilisation as one of four most serious scenarios for abrupt climate change.

The international team onboard the Russian research ship R/V Akademik Keldysh said most of the bubbles currently are dissolving in the water but methane levels at the surface are four to eight times what would normally be expected and this is venting into the atmosphere.

At this moment, there is unlikely to be any major impact on global warming, but the point is that this process has now been triggered. This East Siberian slope methane hydrate system has been perturbed and the process will be ongoing,” said the Swedish scientist Örjan Gustafsson of Stockholm University in a satellite call from the vessel.

The scientists – who are part of a multi-year International Shelf Study Expedition – stressed their findings are preliminary. The scale of methane releases will not be confirmed until they return, analyse the data and have their studies published in a peer-reviewed journal.

But the discovery of potentially destabilised slope frozen methane raises concerns that a new tipping point has been reached that could increase the speed of global heating. The Arctic is considered ground zero in the debate about the vulnerability of frozen methane deposits in the ocean. With the Arctic temperature now rising more than twice as fast as the global average, the question of when – or even whether – they will be released into the atmosphere has been a matter of considerable uncertainty in climate computer models.

The 60-member team on the Akademik Keldysh believe they are the first to observationally confirm the methane release is already under way across a wide area of the slope about 600km offshore.


The latest discovery potentially marks the third source of methane emissions from the region. Semiletov, who has been studying this area for two decades, has previously reported the gas is being released from the shelf of the Arctic – the biggest of any sea.

For the second year in a row, his team have found crater-like pockmarks in the shallower parts of the Laptev Sea and East Siberian Sea that are discharging bubble jets of methane, which is reaching the sea surface at levels tens to hundreds of times higher than normal. This is similar to the craters and sinkholes reported from inland Siberian tundra earlier this autumn.
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morganism

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Re: Permafrost general science thread
« Reply #127 on: October 27, 2020, 11:03:40 PM »
Scary.

Scarier how the russians and asians talk about the hydrate release, and the USA and brits say it will never happen, or will not be catastrophic if it does.

The post about the bacteria above was posted here because it is the only active soil bacteria thread going now.

It appears when the methanotrophs digest the methane, they split out the hydrogen, and release the C.

There is only one researcher working in Antartica, on ice core studies, that is looking at the C in the cores, and he says he thinks the 13/14 shows that the high CO2/CO has signatures that it has been processed by methanotrophs. He also says that in every sample that had bubbles he looked at, that there were dormant methanotrophs.  He believes it is possible that all these gas bubble samples were originally saturated with methane, and that the trophs have slowly been converting over the millennia.
He speculates that the very high geo record of CO2 peaks is actually times that the "hydrate gun" went off, by pointing out that the methanotrophs must have been lofted into the atmosphere to be found in all the ice cores he has looked at.

(citation lost on old hard drive, circa 2003-5 i think)

With the papers postulation of separate populations in the field, if you looked for fossilized bacteria populations in the ice cores, you might be able to ID if they were seabed, soil, or seawater water source. There have been recent studies on the aero populations of microbes of diff families also, they would also likely have a distinct group of families.

kassy

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Re: Permafrost general science thread
« Reply #128 on: October 28, 2020, 08:35:28 PM »
The Permafrost general science thread is mainly for just that. The methane release has it´s own thread:

https://forum.arctic-sea-ice.net/index.php/topic,12.0.html
Welcome to the Arctic Sea Ice Forum - Arctic Methane Topic!

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Re: Permafrost general science thread
« Reply #129 on: November 03, 2020, 04:57:01 AM »
The Observer / Archaeology
Secrets of the ice: unlocking a melting time capsule

https://www.theguardian.com/science/2020/nov/01/secrets-of-the-ice-unlocking-a-melting-time-capsule-archaeology-glaciers


This is Important imo.


Quote
In a year when the unthinkable has become the everyday, when profound changes to lifestyle, economy, travel, ambition and health have been forced upon billions of us by a tiny virus, at a time when science has trumped even the most bombastic rhetoric, it is surely important to stop and reflect on the environmental consequences of our prior economic model. We may soon look back on the Covid-19 pandemic as the good old days before climate change raced away from us.

Will we soon be swapping our smartphones for atlatl, those ingenious ancient spear-throwing devices? It’s too soon to say, but archaeologists have the luxury of a very long view.

“Technological advancement is not permanent. It can fluctuate back and forth,” says Jarman. “We’ve seen that happen throughout human history, and it would be hubris to think that it couldn’t happen again,” he says. “I hope that if it does, that is because we have intentionally managed a soft landing, choosing sustainable technology because we want to, and we know it’s the right thing to do, rather than being forced into it.”

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Sciguy

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Re: Permafrost general science thread
« Reply #130 on: November 10, 2020, 12:51:13 AM »
A just-published study on methane emissions from Siberian lakes shows that the water column of deeper lakes acts as a microbial filter that prevents methane emissions into the atmosphere.

https://bg.copernicus.org/preprints/bg-2020-317/

Quote
Savvichev, A., Rusanov, I., Dvornikov, Y., Kadnikov, V., Kallistova, A., Veslopolova, E., Chetverova, A., Leibman, M., Sigalevich, P., Pimenov, N., Ravin, N., and Khomutov, A.: The water column of the Yamal tundra lakes as a microbial filter preventing methane emission, Biogeosciences Discuss., https://doi.org/10.5194/bg-2020-317, in review, 2020.

Abstract. Microbiological, molecular ecological, biogeochemical, and isotope geochemical research was carried out in four lakes of the central part of the Yamal Peninsula in the area of continuous permafrost. Two of them were large (73.6 and 118.6 ha) and deep (up to 10.6 and 12.3 m) mature lakes embedded into all geomorphological levels of the peninsula, and two others were smaller (3.2 and 4.2 ha) shallow (up to 2.3 and 1.8 m) lakes which appeared as a result of thermokarst on constitutional (segregated) ground ice. We collected samples in August 2019. The Yamal tundra lakes exhibited high phytoplankton production (340–1200 mg C m−2 day−1) during the short summer season. Allochthonous and autochthonous, both particulate and dissolved organic matter was deposited to the bottom sediments, where methane production occurred due to anaerobic degradation (90–1000 µmol СН4 dm−3). The rates of hydrogenotrophic methanogenesis appeared to be higher in the sediments of deep lakes than in those of the shallow ones. In the sediments of all lakes, Methanoregula and Methanosaeta were predominant components of the archaeal methanogenic community. Methane oxidation (1.4–9.9 µmol dm−3 day−1) occurred in the upper sediment layers simultaneously with methanogenesis. Methylobacter tundripaludum (family Methylococcaceae) predominated in the methanotrophic community of the sediments and the water column. The activity of methanotrophic bacteria in deep mature lakes resulted in a decrease of the dissolved methane concentration in lake water from 0.8–4.1 µmol CH4 L−1 to 0.4 µmol CH4 L−1, while in shallow thermokarst lakes the geochemical effect of methanotrophs was much less pronounced. Thus, only small shallow Yamal lakes may contribute significantly to the overall diffusive methane emissions from the water surface during the warm summer season. The water column of large deep lakes on Yamal acts, however, as a microbial filter preventing methane emission into the atmosphere.

 

oren

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Re: Permafrost general science thread
« Reply #131 on: November 20, 2020, 10:08:27 AM »
I wonder what the proportion of lakes in Yamal is between "shallow thermokarst lakes" and "deep mature lakes".

gerontocrat

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Re: Permafrost general science thread
« Reply #132 on: November 20, 2020, 12:10:05 PM »
I wonder what the proportion of lakes in Yamal is between "shallow thermokarst lakes" and "deep mature lakes".
Can one find a nice little table to tell us the answer? NO.

But as far as Western Siberia is concedrned, the topography suggests shallow (see image) and that new small lakes are appearing while large mature lakes are draining.

http://www.izdatgeo.ru/pdf/earth_cryo/2015-2/100_eng.pdf
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Comparative analysis of the above data on the number of the disappeared and newly formed lakes and their total areas in the entire permafrost zone of Western Siberia indicates another important pattern: with the total areas of the disappeared (14,826 hectares) and newly formed lakes (13,649 hectares) lakes, the number of the newly formed lakes is approximately 18 times greater than the number of the disappeared lakes.

Hence, new thermokarst lakes are much smaller in size than the preceding ones. One can suppose then that the observed acceleration of the thermokarst processes caused by climate warming will be accompanied by significant growth in the number of small thermokarst lakes in the permafrost zone of Western Siberia

Acceleration of the thermokarst processes caused by climate warming and noted by many researchers results in more intense formation of new lakes, which is, according to the results obtained, the most characteristic process for the continuous permafrost subzone of Western Siberia. As follows from the above, the newly formed thermokarst lakes are usually small in
size. According to the experimental data by [Audry et al., 2011; Pokrovsky et al., 2011], small thermokarst lakes (in) Western Siberia are plentiful natural sources of methane. Therefore, one can assume increase in the methane emission into the air, as the number of small thermokarst lakes increases in the permafrost zone, which will contribute to intensification of the greenhouse effect.

https://tc.copernicus.org/articles/8/1177/2014/tc-8-1177-2014.pdf
Quote
The acceleration of the permafrost thaw in the northern portion of western Siberia (Kirpotin et al., 2009a, b; Bryksina et al., 2009; Dneprovskaya et al., 2009; Bryksina and Kirpotin, 2012) should increase the amount of small soil subsidence and permafrost depressions while decreasing the amount of large (mature) lakes. For example, a net increase in
the amount of lakes was observed for the Nadym watershed (north of western Siberia and close to continental sites of this #study), which is explained by the formation of small lakes, while the larger lakes fragment after partial drainage (Karlsson et al., 2014).
« Last Edit: November 20, 2020, 12:17:43 PM by gerontocrat »
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Re: Permafrost general science thread
« Reply #133 on: November 20, 2020, 05:05:16 PM »
The large lakes are an established ecosystem so it makes sense that the bacteria over time evolve to take advantage of the extra methane higher in the watercolumn (the research does not strike me as new but it could be for these specific lakes).

All new lakes are shallow thermokarst lakes so it does not mean that much.
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Re: Permafrost general science thread
« Reply #134 on: December 10, 2020, 01:40:18 PM »
A study on soil temperatures in Russia (open access)

https://www.sciencedirect.com/science/article/pii/S092181812030285X?dgcid=rss_sd_all
Significant shallow–depth soil warming over Russia during the past 40 years
Quote

Highlights
• Significant warming of shallow ground occurred in Russia during 1975–2016.

• Trends in soil temperature vary with depth in different frost-related areas.

• For the region as a whole, the intra-annual variability of soil temperature increased.

• Trends in soil temperature significantly respond to changes in snow cover.

3. Results
3.1. Trends in soil temperature from 1975 to 2016
It is found that MAST increased at 279, 286, and 197 sites, while it decreased at 4, 2, and 2 sites, and remained stable (within measurement accuracy) at 32, 31, and 17 sites at depths of 0.8, 1.6, and 3.2 m, respectively (Fig. 2a). The greatest warming of MAST at shallow depths (0.8 and 1.6 m) is 1.09 ± 0.20 °C/decade (mean ± SD, P < 0.01) at a site located in the northern Siberian permafrost area. At a deeper level (3.2 m), the greatest warming in MAST occurred in central Siberia at 0.89 ± 0.12 °C/decade (P < 0.01). However, a few sites that had decreased MAST are mainly located in the permafrost area. Trends in MAST from −0.11 to −0.21 °C/decade were observed at four sites at 0.8 m. For the depths of 1.6 and 3.2 m, MAST of the two sites located in the continuous permafrost area decreased by 0.15 ± 0.09 (P > 0.05) and 0.11 ± 0.05 °C/decade (P > 0.05), respectively, and a decrease in MAST at 3.2 m of 0.36 ± 0.06 °C/decade (P < 0.05) occurred at a seasonal frost site.


3.2. Impact of snow cover characteristics on soil temperature
It is found that MAST was, in general, higher than MAAT, accounting for 0.64 of MAAT at all sites (Fig. 5a). Meanwhile, the sites with smaller SSD and SCD (lighter dots) are closer to the 1:1 line, indicating the role of snow cover in offsetting MAST against MAAT. SSD and SCD were both positively related to ΔT0.8 (Fig. 5b and c), whereas the relations between ΔT0.8 and two snow cover parameters are different, with ΔT0.8–SSD relations being more linear than ΔT0.8–SCD relations. Moreover, SCD shows a higher R2 (0.49) than SSD (0.40) in the linear relationship with ΔT0.8.



Fig. 5. a. Relationships between the mean annual soil temperature (MAST, 0.8 m) and air temperature (MAAT). In total, 9722 annual values at 269 sites during 1975–2016 are scattered with colour representing the annual sum of snow depth (SSD, left) and snow cover duration (SCD, right). b, c. Relationships between the annual offset (ΔT0.8) and SSD (b) and SCD (c) with permafrost distribution.

4. Discussion
The annual mean and extreme soil temperatures of shallow ground significantly increased from 1975 to 2016 in Russia. The majority of the sites had warming trends, and a few sites mainly located in the permafrost areas remained thermally stable and even cooled during the period. The soil warming in the continuous permafrost area was faster than that in the discontinuous permafrost and seasonal frost areas at 0.8 m and 1.6 m, and was slower at 3.2 m (Fig. 4). Moreover, the annual maximum soil temperature increased faster than the minimum soil temperature, which leads to increased intra-annual variability of soil temperature (Fig. 3). The study provides an unprecedentedly detailed picture of soil temperature evolution over the past four decades in Russia by quantifying the trends in the multilayer soil temperature parameters at 457 sites.
« Last Edit: December 10, 2020, 10:36:06 PM by gerontocrat »
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gerontocrat

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Re: Permafrost general science thread
« Reply #135 on: December 10, 2020, 02:05:09 PM »
And a sort of connected study (not open access) on vegetation in the Tundra.

https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.15451?af=R
Divergent shrub‐cover responses driven by climate, wildfire, and permafrost interactions in Arctic tundra ecosystems

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Abstract
The expansion of shrubs across the Arctic tundra may fundamentally modify land–atmosphere interactions. However, it remains unclear how shrub expansion pattern is linked with key environmental drivers, such as climate change and fire disturbance. Here we used 40+ years of high‐resolution (~1.0 m) aerial and satellite imagery to estimate shrub‐cover change in 114 study sites across four burned and unburned upland (ice‐poor) and lowland (ice‐rich) tundra ecosystems in northern Alaska.

Validated with data from four additional upland and lowland tundra fires, our results reveal that summer precipitation was the most important climatic driver (r = 0.67, p < 0.001), responsible for 30.8% of shrub expansion in the upland tundra between 1971 and 2016. Shrub expansion in the uplands was largely enhanced by wildfire (p < 0.001) and it exhibited positive correlation with fire severity (r = 0.83, p < 0.001). Three decades after fire disturbance, the upland shrub cover increased by 1077.2 ± 83.6 m2 ha−1, ~7 times the amount identified in adjacent unburned upland tundra (155.1 ± 55.4 m2 ha−1).

In contrast, shrub cover markedly decreased in lowland tundra after fire disturbance, which triggered thermokarst‐associated water impounding and resulted in 52.4% loss of shrub cover over three decades. No correlation was found between lowland shrub cover with fire severity (r = 0.01). Mean summer air temperature (MSAT) was the principal factor driving lowland shrub‐cover dynamics between 1951 and 2007. Warmer MSAT facilitated shrub expansion in unburned lowlands (r = 0.78, p < 0.001), but accelerated shrub‐cover losses in burned lowlands (r = −0.82, p < 0.001).

These results highlight divergent pathways of shrub‐cover responses to fire disturbance and climate change, depending on near‐surface permafrost and drainage conditions. Our study offers new insights into the land–atmosphere interactions as climate warming and burning intensify in high latitudes.
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kassy

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Re: Permafrost general science thread
« Reply #136 on: December 23, 2020, 04:18:26 PM »
Subsea Permafrost Still Waking Up After 12,000 Years

In the far north, the swelling Arctic Ocean inundated vast swaths of coastal tundra and steppe ecosystems. Though the ocean water was only a few degrees above freezing, it started to thaw the permafrost beneath it, exposing billions of tons of organic matter to microbial breakdown. The decomposing organic matter began producing CO2 and CH4, two of the most important greenhouse gases.

Though researchers have been studying degrading subsea permafrost for decades, difficulty collecting measurements and sharing data across international and disciplinary divides have prevented an overall estimate of the amount of carbon and the rate of release. A new study, led by Ph.D. candidate Sara Sayedi and senior researcher Dr. Ben Abbott at Brigham Young University (BYU) published in IOP Publishing journal Environmental Research Letters, sheds light on the subsea permafrost climate feedback, generating the first estimates of circumarctic carbon stocks, greenhouse gas release, and possible future response of the subsea permafrost zone.

Sayedi and an international team of 25 permafrost researchers worked under the coordination of the Permafrost Carbon Network (PCN), which is supported by the U.S. National Science Foundation. The researchers combined findings from published and unpublished studies to estimate the size of the past and present subsea carbon stock and how much greenhouse gas it might produce over the next three centuries.

Using a methodology called expert assessment, which combines multiple, independent plausible values, the researchers estimated that the subsea permafrost region currently traps 60 billion tons of methane and contains 560 billion tons of organic carbon in sediment and soil. For reference, humans have released a total of about 500 billion tons of carbon into the atmosphere since the Industrial Revolution. This makes the subsea permafrost carbon stock a potential giant ecosystem feedback to climate change.

“Subsea permafrost is really unique because it is still responding to a dramatic climate transition from more than ten thousand years ago,” Sayedi said. “In some ways, it can give us a peek into the possible response of permafrost that is thawing today because of human activity.”

Estimates from Sayedi’s team suggest that subsea permafrost is already releasing substantial amounts of greenhouse gas. However, this release is mainly due to ancient climate change rather than current human activity. They estimate that subsea permafrost releases approximately 140 million tons of CO2 and 5.3 million tons of CH4 to the atmosphere each year. This is similar in magnitude to the overall greenhouse gas footprint of Spain.

The researchers found that if human-caused climate change continues, the release of CH4 and CO2 from subsea permafrost could increase substantially. However, this response is expected to occur over the next three centuries rather than abruptly. Researchers estimated that the amount of future greenhouse gas release from subsea permafrost depends directly on future human emissions. They found that under a business-as-usual scenario, warming subsea permafrost releases four times more additional CO2 and CH4 compared to when human emissions are reduced to keep warming less than 2°C.

“These results are important because they indicate a substantial but slow climate feedback,” Sayedi explained. “Some coverage of this region has suggested that human emissions could trigger catastrophic release of methane hydrates, but our study suggests a gradual increase over many decades.”

Even if this climate feedback is relatively gradual, the researchers point out that subsea permafrost is not included in any current climate agreements or greenhouse gas targets. Sayedi emphasized that there is still a large amount of uncertainty about subsea permafrost and that additional research is needed.

“Compared to how important subsea permafrost could be for future climate, we know shockingly little about this ecosystem,” Sayedi said. “We need more sediment and soil samples, as well as a better monitoring network to detect when greenhouse gas release responds to current warming and just how quickly this giant pool of carbon will wake from its frozen slumber.”

https://www.eurasiareview.com/23122020-subsea-permafrost-still-waking-up-after-12000-years/
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kassy

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Re: Permafrost general science thread
« Reply #137 on: December 23, 2020, 04:22:56 PM »
The researchers found that if human-caused climate change continues, the release of CH4 and CO2 from subsea permafrost could increase substantially. However, this response is expected to occur over the next three centuries rather than abruptly. Researchers estimated that the amount of future greenhouse gas release from subsea permafrost depends directly on future human emissions. They found that under a business-as-usual scenario, warming subsea permafrost releases four times more additional CO2 and CH4 compared to when human emissions are reduced to keep warming less than 2°C.

"These results are important because they indicate a substantial but slow climate feedback," Sayedi explained. "Some coverage of this region has suggested that human emissions could trigger catastrophic release of methane hydrates, but our study suggests a gradual increase over many decades."

Even if this climate feedback is relatively gradual, the researchers point out that subsea permafrost is not included in any current climate agreements or greenhouse gas targets. Sayedi emphasized that there is still a large amount of uncertainty about subsea permafrost and that additional research is needed.

https://www.sciencedaily.com/releases/2020/12/201222081307.htm

bit more detail via SD and the research (OA):

Subsea permafrost carbon stocks and climate change sensitivity estimated by expert assessment
Sayedi, abbott et al
https://iopscience.iop.org/article/10.1088/1748-9326/abcc29


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morganism

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Re: Permafrost general science thread
« Reply #138 on: December 23, 2020, 10:51:20 PM »
interesting at the end of the IOP paper

"One unexpected finding of this research was that the dearth of data on the subsea permafrost domain is partially due to divisions in the subsea permafrost research community. While previous expert assessments on other topics have always involved strong opinions and evidence-based disagreements (Schuur et al 2013, Abbott et al 2016), we found that many invited experts declined to participate or at least expressed serious concerns because of political and territorial considerations, including perceived or real threat of retribution or negative professional consequences. These rifts between research groups and culture of antagonistic competition long precede this paper, as evidenced by unsuccessful synthesis efforts in the past and frequent rebuttals and conflict surrounding published and presented research products (e.g. Thornton et al (2019)). We hope that this exercise, which involved permafrost researchers from many research groups, institutions, career stages, and cultural backgrounds, can contribute to a détente and improvement of collaborative research"

vox_mundi

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Re: Permafrost general science thread
« Reply #139 on: December 24, 2020, 04:50:25 PM »
Earthquakes Generated Permafrost Release; Linkage to Abrupt Arctic Warming: Study
https://phys.org/news/2020-12-great-earthquakes-arctic.html



In the Arctic, one of the factors driving climate warming is the release of methane from permafrost and metastable gas hydrates in the shelf zone. Since researchers began to monitor temperatures in the Arctic, the region has seen two periods of abrupt warming: first in the 1920s and '30s, and then beginning in 1980 and continuing to this day.

Leopold Lobkovsky, member of the Russian Academy of Sciences and the head of the MIPT Laboratory for Geophysical Research of the Arctic and Continental Margins of the World Ocean, hypothesized that the unexplained abrupt temperature changes could have been triggered by geodynamic factors. Specifically, he pointed to a series of great earthquakes in the Aleutian Arc, which is the closest seismically active area to the Arctic.

To test his hypothesis, Lobkovsky had to answer three questions. First, did the dates of the great earthquakes coincide with temperature jumps? Second, what is the mechanism that enables the lithospheric disturbances to propagate over more than 2,000 kilometers from the Aleutian Islands to the Arctic shelf region? Third, how do these disturbances intensify methane emissions?

... It took a model of lithospheric excitation dynamics to answer the second question. The model used by the researcher describes the propagation of so-called tectonic waves and predicts that they should travel at about 100 kilometers per year. This agrees with the delay between each of the great earthquake series and the subsequent temperature hike, as it took the disturbances 15 to 20 years to get transmitted over 2,000 kilometers.

... "There is a clear correlation between the great earthquakes in the Aleutian Arc and the phases of climate warming. A mechanism exists for physically transmitting the stresses in the lithosphere at the appropriate velocities. And these added stresses are capable of destroying metastable gas hydrates and permafrost, releasing methane. Each of the three components in this scheme is logical and lends itself to mathematical and physical explanation. Importantly, it explains a known fact—the abrupt rise in temperature anomalies in the Arctic—which remained unaccounted for by the previous models," Lobkovsky commented.

Leopold Lobkovsky. Seismogenic-Triggering Mechanism of Gas Emission Activizations on the Arctic Shelf and Associated Phases of Abrupt Warming, Geosciences (2020).
https://www.mdpi.com/2076-3263/10/11/428

... or not
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kassy

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Re: Permafrost general science thread
« Reply #140 on: December 24, 2020, 08:13:26 PM »
That is a fun piece. I think there might very well be an effect but not quite the strong one the author claims.

Quote
After this series of huge shocks, the Aleutian island arc has been in seismic “silence” until present time, with no earthquakes having magnitudes higher than 8.0, but the only exception—an M 8.0 event that took place in the central part of the arc in 1986. Thus, one can see there is a 15–20-year lag between the strongest shock series that hit the Aleutian arc, and the beginning of abrupt Arctic warming, which started in 1980.

So 1986 that is also the last year with a global temp under the average. Does that mean anything? I don´t think so. The first red line is related to 3 big ones and the second one is drawn because one happened. Since it happened too late that ruins the causality.

There is also no details on the size of the extra emissions or how they relate to the overall trends.

Earthquakes promoting release of some extra gas: with all that shaking yes, probably. Link to abrupt warming: unproven and by known science caused by other factors for the eighties so overall rating bunk.
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Re: Permafrost general science thread
« Reply #141 on: December 25, 2020, 05:47:14 AM »
From what I've heard about the MOSAIC expeditions, CH4 measurements were taken all over the Arctic seas, including the Siberian ones. It will be interesting to see what they reveal. I tend to think there will be a lean on that

kassy

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Re: Permafrost general science thread
« Reply #142 on: December 25, 2020, 05:09:13 PM »
What do you mean by there will be a lean on that? Do you expect low outcomes or do you mean something else? (Not sure if the sentence is missing just the period or maybe more fell of. 
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Re: Permafrost general science thread
« Reply #143 on: December 26, 2020, 12:48:15 AM »
I tend to think it will probably be in the moderate range

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Re: Permafrost general science thread
« Reply #144 on: February 07, 2021, 11:25:11 PM »
Lawrence et. al 2008 still has the best projection of regional temperature impacts during summer ice free conditions.

One of the several inherent modeling conservatisms in this area is the use of an annual average temperature to project impacts on permafrost.  This is not realistic as the summer warming will be much greater, and the impacts much stronger.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2008GL033985

Accelerated Arctic land warming and permafrost degradation during rapid sea ice loss
GEOPHYSICAL RESEARCH LETTERS, VOL. 35, L11506, doi:10.1029/2008GL033985, 2008

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Re: Permafrost general science thread
« Reply #145 on: February 09, 2021, 06:02:18 PM »
Arctic Permafrost Releases More Carbon Dioxide Than Once Believed
https://phys.org/news/2021-02-arctic-permafrost-carbon-dioxide-believed.html

Research results from an international team, which includes a researcher from the University of Copenhagen among others, suggests that a newly discovered phenomenon will release even larger quantities of CO2 than once supposed from organic matter in permafrost—a pool of carbon previously thought to be bound tightly and safely sequestered by iron.

The amount of stored carbon that is bound to iron and gets converted to CO2 when released is estimated to be somewhere between two and five times the amount of carbon released annually through anthropogenic fossil fuel emissions.

What is new, is that the mineral iron was believed to bind carbon even as permafrost thawed. The new result demonstrates that bacteria incapacitate iron's carbon trapping ability, resulting in the release of vast amounts of CO2. This is an entirely new discovery.

"What we see is that bacteria simply use iron minerals as a food source. As they feed, the bonds which had trapped carbon are destroyed and it is released into the atmosphere as greenhouse gas," explains Associate Professor Carsten W. Müller of the University of Copenhagen's Department of Geosciences and Natural Resource Management. He elaborates:

"Frozen soil has a high oxygen content, which keeps iron minerals stable and allows carbon to bind to them. But as soon as the ice melts and turns to water, oxygen levels drop and the iron becomes unstable. At the same time, the melted ice permits access to bacteria. As a whole, this is what releases stored carbon as CO2," explains Müller.

... "This means that we have a large new source of CO2 emissions that needs to be included in climate models and more closely examined," says Carsten W. Müller.

The study has just been published in Nature Communications.

Monique S. Patzner et al, Iron mineral dissolution releases iron and associated organic carbon during permafrost thaw, Nature Communications (2020)
https://www.nature.com/articles/s41467-020-20102-6
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Sciguy

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Re: Permafrost general science thread
« Reply #146 on: February 10, 2021, 09:04:20 PM »
^^^
How much of the current carbon released by the Arctic is a result of this mechanism?

How much more carbon would be released?

From reading the paper, this isn't a new way for carbon to be released, it's just a way for carbon to be released that hadn't been realized before.

Also, if you read the methods section of the paper  it appears that the method used to detect this effect doesn't recreate actual on site conditions.  From the methods section of the paper:

Quote
Given the restrictions in place, it was only possible to collect six cores per each thaw stage over three field campaigns (2017, 2018, and 2019) (Supplementary Figs. 1–5).

Quote
The cores were kept in a vertical position during transfer into an anoxic glovebox (100% N2).

Quote
The soil cores were removed from their liners under a N2 atmosphere. Each core was sectioned into an organic horizon of varying thickness (4–10 cm), a transition zone (3–5 cm), and mineral horizon (4–10 cm) (Supplementary Fig. 1), following Ryden et al.27

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The soil layers were subjected to several chemical extractions to quantify the different iron phases. The soils were kept frozen prior to analysis, then dried at 20 °C under anoxic conditions until no further weight loss was observed (1 day).

Quote
Following the extraction, as detailed below, all samples were centrifuged at room temperature for 10 min at 5300×g. After centrifugation, the supernatant was decanted into another 10 mL glass vial. Each extraction was performed in duplicates for each layer. Throughout the extraction, samples were kept in the dark under anoxic conditions (N2 atmosphere). The extracts were analyzed for Fe and DOC as described above. Additionally, the samples were acidified in 1% (v/v) HNO3 and analyzed in duplicates by microwave plasma atomic emission spectroscopy (MP-AES)/inductively coupled plasma mass spectrometry (ICP-MS).

It's possible that the methods used in this experiment would have killed off existing bacteria that are known to consume carbon containing compounds.

The discussion section of the paper acknowledged the key role that bacteria play in determining carbon emissions from soils.

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It should be kept in mind that it is not only the released carbon that can directly contribute to greenhouse gas emissions. The reduction of Fe(III) itself will also contribute to CO2 emissions since it is directly coupled to the oxidation and mineralization of organic carbon. On the other hand, since Fe(III) reduction is more thermodynamically favorable, conditions more suitable for Fe(III)-reducers can also inhibit methanogenesis46. However, Fe(III) reduction consumes protons and leads to an increase in pH which can make conditions more favorable for methanogens47. Along the thaw gradient, an increase in pH and an increasing abundance of methanogens has been reported24. Acetotrophic methanogens can use Fe(III) reduction to maximize energy conservation from metabolism of acetate48. Shifts in CH4 production pathway from CO2 reduction to acetate cleavage along the thaw gradient was previously described21,24. At the same time, anaerobic oxidation of methane by methanotrophs can also be coupled to Fe(III) reduction. An increase in methane oxidation rates along the thaw gradient has been shown by Perryman et al.26. Our data clearly show that reactive Fe phases serve as an important and overlooked, terminal electron acceptor along the thaw gradient and thus could exert a significant control on net methane emissions.


vox_mundi

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Re: Permafrost general science thread
« Reply #147 on: April 29, 2021, 05:27:15 PM »
Methane Release Rapidly Increases In the Wake of the Melting Ice Sheets
https://phys.org/news/2021-04-methane-rapidly-ice-sheets.html

Several studies show that the most recent deglaciation, Holocene (approximately 21ka-15ka ago) of the Barents Sea has had a huge impact on the release of methane into the water. A most recent study in Geology looks even further into the past, some 125 000 years ago, and contributes to the conclusion: Melting of the Arctic ice sheets drives the release of the potent greenhouse gas methane from the ocean floor.

"In our study, we expand the geological history of past Arctic methane release to the next to last interglacial, the so-called Eemian period. We have found that the similarities between the events of both Holocene and Eemian deglaciation advocate for a common driver for the episodic release of geological methane—the retreat of ice sheets." says researcher Pierre-Antoine Dessandier, who conducted this study as a postdoctoral fellow at CAGE Centre for Arctic Gas Hydrate Environment and Climate at UiT The Arctic University of Norway.

The study is based on measurements of different isotopes found in sediment cores collected from the Arctic Ocean.

"The isotopic record showed that as the ice sheet melted and pressure on the seafloor lessened during the Eemian, methane was released in violent spurts, slow seeps, or a combination of both. By the time the ice disappeared completely, some thousands of years later, methane emissions had stabilized." says Dessandier.

"The present-day acceleration of Greenlands ice melt is an analogue to our model. We believe that the future release of methane from below and nearby these ice sheets is likely," says Dessandier.



P.-A. Dessandier et al, Ice-sheet melt drove methane emissions in the Arctic during the last two interglacials, Geology (2021)
https://pubs.geoscienceworld.org/gsa/geology/article-abstract/doi/10.1130/G48580.1/595627/Ice-sheet-melt-drove-methane-emissions-in-the?redirectedFrom=fulltext
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gerontocrat

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Re: Permafrost general science thread
« Reply #148 on: April 30, 2021, 04:20:24 PM »
Siberian permafrost becoming a more dynamic system

https://www.sciencedirect.com/science/article/pii/S1674927821000538?dgcid=rss_sd_all
Permafrost dynamics and their hydrologic impacts over the Russian Arctic Drainage Basin
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Abstract
Permafrost is an important component in hydrological processes because changes in runoff over the Arctic drainage basin cannot be well explained by changes in precipitation-related variables. However, current understanding of the influences of permafrost on hydrological dynamics is insufficient. This study investigated historical variations in permafrost conditions and their potential hydrologic effects over the Russian Arctic drainage basin. The results show that soil temperature (at 0.40 m below surface) has increased about 1.4°C over the Ob, 1.5°C over the Yenisei, and 1.8°C over the Lena River basin from 1936 through 2013, possibly resulted in a significant thawing of permafrost. Rapid active layer changes have occurred since the 1970s. The volume of the active layer increased by 28, 142, and 228 km3 over the Ob, Yenisei, and Lena basins, respectively, since the 1970s. Melting ground ice caused by deepening active layer may be a limited contribution to annual runoff. Runoff during freeze season (October‒April) showed significant positive correlations (p < 0.05) to active layer thickness in the Yenisei and Lena basins
while negative correlation (p > 0.05) in the Ob basin. These results imply that, in basins with high permafrost coverage, a deeper active layer increased soil water storage capacity and perhaps contribute to an increase in winter runoff.
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gerontocrat

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Re: Permafrost general science thread
« Reply #149 on: April 30, 2021, 11:37:33 PM »
Just shows that part of the story is not in the high latitudes of the Northern hemisphere

Open Access...
https://iopscience.iop.org/article/10.1088/1748-9326/abf7f0/pdf
https://iopscience.iop.org/article/10.1088/1748-9326/abf7f0#erlabf7f0s3
Accelerating permafrost collapse on the eastern Tibetan Plateau
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1. Introduction
Permafrost temperature has increased globally by an average of 0.29 ± 0.12 °C from 2007 to 2016 across polar and high mountain regions (IPCC 2019). Persistent and widespread warming is causing permafrost degradation, which is projected to continue this century and beyond (IPCC 2019, Turetsky et al 2020). Substantial changes to hydrological conditions and biogeochemical cycling may occur following permafrost degradation because of exposure of previously frozen organic matter and mineral soil, changes in water balance due to inundation or drying, and thermal shifts due to changes in snow distribution and vegetation (Vonk et al 2015, Liljedahl et al 2016).

In areas with excess ground ice, permafrost thaw could trigger surface collapse or thermokarst, which rapidly expose and thaw large quantities of organic matter, potentially stimulating production of carbon and nitrogen greenhouse gases (Abbott et al 2015, Schuur et al 2015, Turetsky et al 2020). An abruptly increasing frequency and magnitude of permafrost collapse has been reported for the pan-Arctic regions of Canada, Alaska, and Siberia (Vonk et al 2012, Abbott et al 2015, Liljedahl et al 2016, Olefeldt et al 2016, Farquharson et al 2019). In these areas, permafrost collapse has altered the frequency and intensity of ecosystem disturbances, potentially creating significant feedbacks to climate change (Vonk and Gustafsson 2013, Schuur et al 2015).

Outside of the Arctic and Boreal biomes, the Tibetan Plateau contains the largest permafrost region. Also known as the Third Pole and the Water Tower of Asia, the Tibetan Plateau covers an area of 1.35 × 106 km2 (about one eighth of China's territory), 67% of which is underlain by permafrost (Zou et al 2017). Additionally, the plateau and its surroundings are the source of major Asian rivers, including the Yangtze River, the Yellow River, the Brahmaputra River and the Ganges River, which provide water to 1.4 billion people (Yao et al 2019). Permafrost thaw, retreating glaciers and decreasing snow cover profoundly influence hydrology in the region, impacting regional water quantity and quality (Yang et al 2014, Gao et al 2019, Daout et al 2020, Mu et al 2020, Wang et al 2020, Chang et al 2021).

A substantial gap exists in our understanding of how permafrost degradation affect landforms and how permafrost degradation distribute and potentially accelerate changes to the cryosphere system of the Tibetan Plateau. In contrast to the predominantly flat landscape of Boreal and Arctic regions where most research has been carried out, the Tibetan Plateau has complex and steeper topography with abundant mountains. This may cause the Tibetan Plateau permafrost system to be more vulnerable to thermokarst and other landscape collapse processes (Mu et al 2020, Chang et al 2021). Furthermore, the mean annual temperature on the Tibetan Plateau has increased by 0.3 °C–0.4 °C per decade since the 1960s, more than twice the global average (Chen et al 2015). The accelerated temperature increase also contributes to the significant permafrost degradation (Mu et al 2020).

A new estimate of soil carbon stock on the Tibetan Plateau down to a 3 m depth was 36.6 Gt C, which is double to triple the amount predicted earlier by ecosystem models (Ding et al 2019). Some recent research demonstrated that permafrost collapse on the Tibetan Plateau is leading to losses of soil carbon (Mu et al 2016, 2020, Liu et al 2018, Wang et al 2020, Chang et al 2021). Effects of permafrost collapse on changes in methane flux and soil bacterial communities have also been observed for the Tibetan Plateau (Wu et al 2018, Yang et al 2018).

Permafrost collapse is one of the most significant degradation processes in the plateau, which may enhance the carbon release and/or damage the current permafrost status.

3.2. Acceleration of permafrost collapse
The number and extent of permafrost collapse features on the eastern Tibetan Plateau have increased since the baseline observations in 1969, with most new collapses occurring between the 1997–2004 and the 2017 observational periods (figures 1(b)–(e) and table S3). From 1969 to 2017, the numbers and areas of permafrost collapse features have increased approximately by a factor of 12 and 40, respectively, and the area and number of permafrost collapses has increased with a range of 1%–5% per year and 4%–18% per year, respectively (figures 1(f) and (g)). Only about 8% of the current features are present in 1969, while 80% are present by the period 1997–2004, with the remainder of collapsing sites added since then (table S3). While the total areal extent of these collapse features increases ten-fold between 1969 and 1997–2004, 70% of the total collapse area in the study regions has been added since 1997–2004 to the present (in 2017). Hence, while most new occurrences emerge between 1969 to 1997–2004, most of the areal extent has been added in the most recent period.

4. Conclusions
The Tibetan Plateau cryosphere has been experiencing rapid changes due to climate warming. Permafrost collapse has in the recent period emerged as a widespread phenomenon on the plateau, which play a pivotal role on hydrological and ecological processes in the cryospheric regions. Our study on distribution and temporal variations of permafrost collapse in the eastern Tibetan Plateau extend our knowledge on rapid permafrost thaw in the third pole region. For the individual collapse measurements, more than 50% of the lost volume are due to the ground ice melt. Combined with the permafrost collapse, plenty of organic carbon was released to the downstream ecosystems. The rate of permafrost has been accelerated since 1970s in the region, further deepening insights into the linkage between climate change and permafrost carbon feedback in the future. Long-term observations of permafrost collapse systems like the present study are required to improve our ability to both understand and anticipate their potential impact on local ecosystems and on the large-scale permafrost climate feedbacks.



click to enlarge very large image attached
"Para a Causa do Povo a Luta Continua!"
"And that's all I'm going to say about that". Forrest Gump
"Damn, I wanted to see what happened next" (Epitaph)